Balanced Circuit

A balanced circuit, whether for AC or DC, typically refers to a configuration where there are two conductors (or signals) that are at equal but opposite potentials with respect to ground. Here’s a breakdown of what this means:

1. AC Balanced Circuit: In alternating current (AC) circuits, balance often refers to a specific configuration where signals are transmitted differentially. This means that there are two conductors: one carries the original signal, and the other carries an inverted version of the same signal. These signals are referenced to ground, where the potential difference between the two conductors is equal and opposite at every instant. This configuration helps in reducing interference and noise pickup because any noise induced on the transmission line affects both conductors equally, allowing the differential receiver to cancel out the noise.
2. DC Balanced Circuit: In direct current (DC) circuits, balance similarly implies a state where two conductors or signals have equal but opposite potentials with respect to ground. This might be seen in certain signaling or control circuits where differential signaling is employed for noise immunity and reliable transmission over longer distances.
3. Applications: Balanced circuits are commonly used in various applications such as audio equipment (balanced audio lines), telecommunications (DSL lines), and data transmission (Ethernet cables). They provide advantages in terms of noise rejection, increased signal integrity, and improved common-mode rejection ratio (CMRR).
4. Differential Signaling: The key principle in balanced circuits is differential signaling, where the receiver detects the voltage difference between the two conductors rather than the absolute voltage with respect to ground. This differential mode of operation allows for robust transmission even in the presence of electromagnetic interference (EMI) and ground potential differences.

In summary, a balanced circuit ensures that two signals or conductors are maintained at equal and opposite potentials relative to ground, offering benefits in terms of noise immunity and signal integrity in both AC and DC applications.